Field of the Disclosure
The present disclosure relates to a solar cell and a method of manufacturing the same.
Description of the Related Art
Graphene, a two-dimensional carbon nanomaterial, has low sheet resistance, high electrical conductivity, high transmittance, and high mechanical strength, and thus has been increasingly utilized in next-generation displays, such as flexible displays and touch panels, in the energy industry, such as solar cells, and in various electronics such as smart windows and RFID.
In recent years, graphene has attracted considerable attention due to potential thereof for the growth of industrial technology as well as the development of basic science. In particular, a technique of manufacturing large-area graphene was recently developed, whereby application possibility thereof is increasing.
Among large-area graphene products, graphene manufactured by chemical vapor deposition (CVD), which is widely used in the industry, has a large area and high transmittance and electrical conductivity, thereby being expected to be applied as a transparent electrode. Displays, transistors and solar cells based on graphene produced by chemical vapor deposition have also been developed.
Recently, the possibility of manufacture of solar cells through fusion and convergence of graphene and bulk silicon has been suggested. However, since bulk silicon cannot control bandgap energy, there have been problems in achieving ideal device performance through combination with graphene. Accordingly, if the bandgap energy of silicon can be controlled and the electrical properties of graphene can be controlled, an excellent and ideal solar cell can be manufactured.
Unlike bulk silicon, bandgap of silicon quantum dots can be controlled by controlling the sizes of the quantum dots due to the quantum confinement effect (QCE) thereof.
In particular, silicon quantum dots can be protected in air by forming the silicon quantum dots inside silicon dioxide (SiO2) and, upon bonding with graphene, the contact characteristics of the silicon quantum dots can be improved. Accordingly, solar cell efficiency can be improve.
Meanwhile, a metal, such as gold or aluminum, has been used as a raw material of an electrode of a silicon quantum dot solar cell, whereby such an opaque metal electrode blocks a portion of sunlight. In addition, since such a metal electrode has a mesh structure, great loss occurs in trapping charge carriers generated by sunlight, whereby there is limitation in increasing efficiency.
To overcome these problems, a transparent electrode, such as an indium tin oxide (ITO) electrode, can be used. However, such a transparent electrode is expensive and it is difficult to control the optical and electrical characteristics thereof, whereby it is very difficult to maximize the efficiency of a solar cell.
On the other hand, graphene has excellent electrical conductivity, and excellent transmittance compared to metals and other transparent electrode materials. In addition, since graphene has a high work function, contact properties with silicon quantum dots can be improved. Further, since the work function can be controlled by doping with graphene, efficiency can be maximized when graphene is combined with a solar cell.